bathroom floor

[paulpa]

looking at installing the floor in the bathroom that will be tiled.
Is 18mm exterior ply direct to floor joists enough or is 25mm advisable screwed down at correct intervals?

 

[Richard C]

Depends on the joist size/pitch/span, what are they?

 

[paulpa]

400 centres 225 x 50 joists

 

[Richard C]

Sounds good but what is the span (distance between the joist supports)?

 

[paulpa]

3m

 

[Richard C]

With that joist spec, you should be OK with 18mm WBP at 3m as long as the joists are in good condition with no flex or movement & you use quality tiling materials. Don’t know your joist layout but use the biggest boards you can with the minimum number of joints & avoid cross board joints in the centre of the room. Board long edge along the centre line of a joist if you can & support any cross board joints with tight fitting noggins between the joists, minimum 4” x 2”. It’s generally not necessary to fit noggins around the two unsupported edges on the perimeter of the room unless they coincide with a door threshold or will be subject to any appreciable load. Screw fix 35mm into the joists every 150mm. Acrylic seal the back of the ply before you lay it & reinforce tape all the joints; don’t prime the tile surface unless you adhesive manufacturer recommends you do so.

Read the tiling sticky & Tiling forum archive post as there are still many things that can catch you out. Only use a quality trade flexible powder adhesive for floors suitable for your tiles; don’t use cheap own brand or DIY tiling materials they are generally crap.

 

[paulpa]

thank you.

 

[Richard C]

thank you.

If you mean it, hit the thanks button top right